Earth Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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Late-glacial alpine glacier advance and early Holocene tephras, northern British Columbia

Date created: 
2006
Abstract: 

Two related studies in northern British Columbia are presented. The first documents moraines in Finlay River area that record an advance of alpine glaciers. A minimum age of 9230 radiocarbon yr BP and the relation of moraines to ice-stagnation deposits suggest the advance is Younger Dryas in age. The advance demonstrates Younger Dryas glacier expansion differs in magnitude in western Canada, suggesting a complex glacier response to late-glacial climate change. The second study describes four early Holocene tephras. Two phonolitic tephras, older than 9180 radiocarbon yr BP, were found in sediments from Finlay River and Dease Lake areas. Their source may be a large volcano in northwest British Columbia. Two other tephras were recovered from Bob Quinn Lake. A lower basaltic tephra was produced by an eruption near Iskut River 8400 radiocarbon yr ago. The upper phonolitic tephra is 6000-7000 radiocarbon yr old.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

A multi-parameter investigation of volcanic plume behavior and resultant environmental impact at a persistently degassing volcano, Masaya, Nicaragua

Date created: 
2006
Abstract: 

Recent advances in volcanic gas sensing technology make possible detailed investigations of the behavior of boundary layer gas plumes. An intensive survey of SO2 flux during two month-long campaigns revealed an apparent decrease of 30-50% downwind of Masaya volcano, Nicaragua. Dry deposition of S and aerosol conversion cannot account for such losses. Local topography modifies regional trade winds, causing plume acceleration. The resulting along-axis dilution of the plume leads to underestimates of total SO2 emissions. This apparent depletion can be accounted for by accurate determination of plume speed at the location of each SO2 flux measurement. Interaction of acidic plumes with elevated topography results in widespread vegetation damage downwind, which may be characterized by a multi-parameter approach incorporating ground-based datasets and Landsat NDVIs at Masaya and other volcanic systems. A thorough understanding of plume behavior is essential for accurate evaluation of volcanic SO2 output and resultant environmental impacts.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Geology and tectonics of the Nootka Island region, British Columbia

Author: 
Date created: 
2006
Abstract: 

Nootka Island represents a portion of an accreted volcanoplutonic arc, on the western coast of Vancouver Island, British Columbia, of the Canadian Cordillera Insular Belt . This work provides a 1:110,000 scale geologic map and synthesises the regional tectonics. Two main protolith groups are evident on Nootka Island. Group 1 contains tholeiitic basalts that have within-plate / E-MORB element signatures. Limestones and siltstones comprise the intervening sedimentary strata. Group 2 comprises the youngest and consists of calc-alkaline, arc-like basalts, a plutonic suite, and minor hypabyssal bodies. Groups 1 and 2 resemble the Triassic Karmutsen and Jurassic Bonanza Formations. Plagioclase-hornblende thermometry and aluminium-in-hornblende barometry indicate metamorphism at up to 710o Celsius and 3.2 kbar of early Jurassic and older rocks. Whole rock argon dating of a basalt dyke post-deformation reveals crystallization ages of 168 Ma, and metamorphism at 158 Ma from an older Group 1 hyaloclastite

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Characterization of the Zymoetz river rock avalanche

Date created: 
2005
Abstract: 

On June 8, 2002, the Pacific Northern Gas pipeline in the Zymoetz River valley was severed over a distance of tens of meters by a large debris flow. The event initiated as a rock avalanche in Glen Falls Creek, a tributary of the 6 3 Zymoetz River. The rock avalanche involved I XI 0 m of volcaniclastic bedrock, and travelled through a complex flow path, to finally deposit a large fan in the main Zymoetz River. Approximately half of the debris volume was deposited in the cirque basin at the head of the valley, with the rest deposited in the channel, and the fan. Photoanalysis software has offered insights into the grain size distributions throughout the deposit. Application of the modelling programs DAN-W IDAN3D has significantly increased our understanding of the dynamics of the event.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

A multi-disciplinary study of Port Eliza cave sediments and their implications for human coastal migration

Date created: 
2005
Abstract: 

A multi-disciplinary study at Port Eliza cave on Vancouver Island has refined the timing and character of late Wisconsinan environments and has significant implications for the Human Coastal Migration Hypothesis. Loss-on-ignition, paleomagnetic and sedimentological data show that there was continuous sedimentation through the last glacial maximum, implying a warmbased Cordilleran Ice Sheet. Radiocarbon dating supported by paleomagnetic data and U/Th ages constrain the time of maximum glaciation to between ca. 16 and 12.5 ka BP. Terrestrial floral and faunal data indicate a pre-Last Glacial Maximum, cold, dry, steppe environment with rare trees but a diverse fauna. Marine fossils represent a rich, dominantly nearshore fauna and suggest the sea was close to the cave. These data indicate that ice-free conditions lasted until at least 16 ka BP, and suggest that prior to the late Wisconsinan glacial maximum, humans could have survived on a mixed marine-terrestrial diet in the Port Eliza area.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Application of geophysics and numerical modelling in studying aquifer heterogeneity and nitrate transport, Abbotsford-Sumas aquifer, British Columbia, and Washington, USA

Date created: 
2006
Abstract: 

Heterogeneity within the sand and gravel deposits of the Abbotsford-Sumas aquifer has a significant impact upon groundwater movement and nitrate transport. Using GPR and borehole logging, the scale of heterogeneity was determined, with fining upward sequences up to 5 m thick and continuous over 10’s of metres. Smaller heterogeneities were also identified visually in a local gravel pit. Various approaches were examined to represent this heterogeneity within a local groundwater flow mode l. The use of vertical anisotropy proved to be most realistic. Ages determined from the model were 60-80% lower than measured isotopic ages due to the inability to adequately represent the tortuosity of the flow paths. The spatial distribution and temporal variation of nitrate in the aquifer provided initial and calibration nitrate concentrations for the nitrate transport model. Nitrate concentrations thought to be reaching the aquifer based on recent BMPs are not sufficient to produce the observed nitrate concentrations.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Influence of aquifer heterogeneity on the design and modelling of Aquifer Thermal Energy Storage (ATES) systems

Author: 
Date created: 
2006
Abstract: 

A modelling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in aquifer thermal energy storage (ATES) systems. An existing ATES system installed within a heterogeneous aquifer system in Agassiz, British Columbia, Canada was used as a case study. Two 3D heat transport models of the study site were developed and calibrated using the heat transport code FEFLOW, including: a "simple" model domain with uniform hydraulic and thermal properties (no layering); and, a "complex" aquifer domain with variable hydraulic and thermal properties assigned to discrete layers to represent aquifer heterogeneity. Comparison of simulation results indicated heat transport in higher permeability layers was significant. Effects of heterogeneity on thermal energy storage and recoverability were not observed. Heat transport in the aquifer was determined to be more sensitive to properties and boundary conditions which influence convective heat transport.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Quantifying heterogeneity in variably fractured rock using a hydrostructural domain approach, Gulf Islands, British Columbia

Author: 
Date created: 
2006
Abstract: 

A hydrostructural domain approach is used to derive hydraulic properties for the fractured bedrock aquifers of the Gulf Islands, British Columbia, Canada. Domains are defined using fracture intensity and modeled using a stochastic, discrete fracture network-equivalent porous medium (DFN-EPM) approach. Results show that the "highly" fractured interbedded sandstone and mudstone (1.0 m spacing) domain. The two highly fractured domains have an average permeability of 1 0-13 m2 compared to 1 0-14 m2 for the less fractured domain. The model results also show a westward decrease in transmissivity, porosity and permeability. This decrease appears to be associated with the hinge line of a large anticline. Independently collected pumping test data support this interpretation. The DFN-EPM approach used in this thesis may have applications to other areas where groundwater resources in fractured rock aquifers are of interest.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)

Fluvial response to late Holocene glacier fluctuations in the Nostetuko River valley, southern Coast Mountains, British Columbia

Date created: 
2006
Abstract: 

Late Holocene glacier fluctuations and changes in bed elevation are recorded in the alluvial fill of the west fork Nostetuko River valley, southern Coast Mountains, British Columbia. Valley-wide aggradation coincides with periods of local and regional glacier advance on centennial timescales. Peat layers containing in situ tree roots and stumps formed during periods of floodplain stability that coincide with intervals when glaciers were restricted. Radiocarbon ages on roots, tree stems, and woody plant detritus in the peat layers record five major phases of Holocene glacier advance, the most recent at the culmination of the Little Ice Age. A high-resolution record of Little Ice Age glacier fluctuations was derived by cross-dating ring-width series of fossil trees in the peat layers with a previously established master ring-width chronology and by constraining floating ring-width chronologies with radiocarbon ages.

Document type: 
Thesis
File(s): 
Department: 
Department of Earth Sciences - Simon Fraser University
Thesis type: 
Thesis (M.Sc.)